The first rule takes precedence in the case of a single <commit>. To
apply the second rule, i.e., format everything since the beginning of
history up until <commit>, use the --root option: git format-patch
--root <commit>. If you want to format only <commit> itself, you
can do this with git format-patch -1 <commit>.

By default, each output file is numbered sequentially from 1, and uses the
first line of the commit message (massaged for pathname safety) as
the filename. With the --numbered-files option, the output file names
will only be numbers, without the first line of the commit appended.
The names of the output files are printed to standard
output, unless the --stdout option is specified.

If -o is specified, output files are created in <dir>. Otherwise
they are created in the current working directory.

By default, the subject of a single patch is "[PATCH] First Line" and
the subject when multiple patches are output is "[PATCH n/m] First
Line". To force 1/1 to be added for a single patch, use -n. To omit
patch numbers from the subject, use -N.

If given --thread, git-format-patch will generate In-Reply-To and
References headers to make the second and subsequent patch mails appear
as replies to the first mail; this also generates a Message-Id header to
reference.

OPTIONS

-p

--no-stat

Generate plain patches without any diffstats.

-U<n>

--unified=<n>

Generate diffs with <n> lines of context instead of
the usual three.

--minimal

Spend extra time to make sure the smallest possible
diff is produced.

--patience

Generate a diff using the "patience diff" algorithm.

--stat[=<width>[,<name-width>[,<count>]]]

Generate a diffstat. You can override the default
output width for 80-column terminal by --stat=<width>.
The width of the filename part can be controlled by
giving another width to it separated by a comma.
By giving a third parameter <count>, you can limit the
output to the first <count> lines, followed by
... if there are more.

These parameters can also be set individually with --stat-width=<width>,
--stat-name-width=<name-width> and --stat-count=<count>.

--numstat

Similar to --stat, but shows number of added and
deleted lines in decimal notation and pathname without
abbreviation, to make it more machine friendly. For
binary files, outputs two - instead of saying
0 0.

--shortstat

Output only the last line of the --stat format containing total
number of modified files, as well as number of added and deleted
lines.

--dirstat[=<param1,param2,...>]

Output the distribution of relative amount of changes for each
sub-directory. The behavior of --dirstat can be customized by
passing it a comma separated list of parameters.
The defaults are controlled by the diff.dirstat configuration
variable (see git-config(1)).
The following parameters are available:

changes

Compute the dirstat numbers by counting the lines that have been
removed from the source, or added to the destination. This ignores
the amount of pure code movements within a file. In other words,
rearranging lines in a file is not counted as much as other changes.
This is the default behavior when no parameter is given.

lines

Compute the dirstat numbers by doing the regular line-based diff
analysis, and summing the removed/added line counts. (For binary
files, count 64-byte chunks instead, since binary files have no
natural concept of lines). This is a more expensive --dirstat
behavior than the changes behavior, but it does count rearranged
lines within a file as much as other changes. The resulting output
is consistent with what you get from the other --*stat options.

files

Compute the dirstat numbers by counting the number of files changed.
Each changed file counts equally in the dirstat analysis. This is
the computationally cheapest --dirstat behavior, since it does
not have to look at the file contents at all.

cumulative

Count changes in a child directory for the parent directory as well.
Note that when using cumulative, the sum of the percentages
reported may exceed 100%. The default (non-cumulative) behavior can
be specified with the noncumulative parameter.

<limit>

An integer parameter specifies a cut-off percent (3% by default).
Directories contributing less than this percentage of the changes
are not shown in the output.

Example: The following will count changed files, while ignoring
directories with less than 10% of the total amount of changed files,
and accumulating child directory counts in the parent directories:
--dirstat=files,10,cumulative.

--summary

Output a condensed summary of extended header information
such as creations, renames and mode changes.

--no-renames

Turn off rename detection, even when the configuration
file gives the default to do so.

--full-index

Instead of the first handful of characters, show the full
pre- and post-image blob object names on the "index"
line when generating patch format output.

--binary

In addition to --full-index, output a binary diff that
can be applied with git-apply.

--abbrev[=<n>]

Instead of showing the full 40-byte hexadecimal object
name in diff-raw format output and diff-tree header
lines, show only a partial prefix. This is
independent of the --full-index option above, which controls
the diff-patch output format. Non default number of
digits can be specified with --abbrev=<n>.

-B[<n>][/<m>]

--break-rewrites[=[<n>][/<m>]]

Break complete rewrite changes into pairs of delete and
create. This serves two purposes:

It affects the way a change that amounts to a total rewrite of a file
not as a series of deletion and insertion mixed together with a very
few lines that happen to match textually as the context, but as a
single deletion of everything old followed by a single insertion of
everything new, and the number m controls this aspect of the -B
option (defaults to 60%). -B/70% specifies that less than 30% of the
original should remain in the result for git to consider it a total
rewrite (i.e. otherwise the resulting patch will be a series of
deletion and insertion mixed together with context lines).

When used with -M, a totally-rewritten file is also considered as the
source of a rename (usually -M only considers a file that disappeared
as the source of a rename), and the number n controls this aspect of
the -B option (defaults to 50%). -B20% specifies that a change with
addition and deletion compared to 20% or more of the file's size are
eligible for being picked up as a possible source of a rename to
another file.

-M[<n>]

--find-renames[=<n>]

Detect renames.
If n is specified, it is a threshold on the similarity
index (i.e. amount of addition/deletions compared to the
file's size). For example, -M90% means git should consider a
delete/add pair to be a rename if more than 90% of the file
hasn't changed.

-C[<n>]

--find-copies[=<n>]

Detect copies as well as renames. See also --find-copies-harder.
If n is specified, it has the same meaning as for -M<n>.

--find-copies-harder

For performance reasons, by default, -C option finds copies only
if the original file of the copy was modified in the same
changeset. This flag makes the command
inspect unmodified files as candidates for the source of
copy. This is a very expensive operation for large
projects, so use it with caution. Giving more than one
-C option has the same effect.

-D

--irreversible-delete

Omit the preimage for deletes, i.e. print only the header but not
the diff between the preimage and /dev/null. The resulting patch
is not meant to be applied with patch nor git apply; this is
solely for people who want to just concentrate on reviewing the
text after the change. In addition, the output obviously lack
enough information to apply such a patch in reverse, even manually,
hence the name of the option.

When used together with -B, omit also the preimage in the deletion part
of a delete/create pair.

-l<num>

The -M and -C options require O(n^2) processing time where n
is the number of potential rename/copy targets. This
option prevents rename/copy detection from running if
the number of rename/copy targets exceeds the specified
number.

-O<orderfile>

Output the patch in the order specified in the
<orderfile>, which has one shell glob pattern per line.

-a

--text

Treat all files as text.

--ignore-space-at-eol

Ignore changes in whitespace at EOL.

-b

--ignore-space-change

Ignore changes in amount of whitespace. This ignores whitespace
at line end, and considers all other sequences of one or
more whitespace characters to be equivalent.

-w

--ignore-all-space

Ignore whitespace when comparing lines. This ignores
differences even if one line has whitespace where the other
line has none.

--inter-hunk-context=<lines>

Show the context between diff hunks, up to the specified number
of lines, thereby fusing hunks that are close to each other.

-W

--function-context

Show whole surrounding functions of changes.

--ext-diff

Allow an external diff helper to be executed. If you set an
external diff driver with gitattributes(5), you need
to use this option with git-log(1) and friends.

--no-ext-diff

Disallow external diff drivers.

--textconv

--no-textconv

Allow (or disallow) external text conversion filters to be run
when comparing binary files. See gitattributes(5) for
details. Because textconv filters are typically a one-way
conversion, the resulting diff is suitable for human
consumption, but cannot be applied. For this reason, textconv
filters are enabled by default only for git-diff(1) and
git-log(1), but not for git-format-patch(1) or
diff plumbing commands.

--ignore-submodules[=<when>]

Ignore changes to submodules in the diff generation. <when> can be
either "none", "untracked", "dirty" or "all", which is the default
Using "none" will consider the submodule modified when it either contains
untracked or modified files or its HEAD differs from the commit recorded
in the superproject and can be used to override any settings of the
ignore option in git-config(1) or gitmodules(5). When
"untracked" is used submodules are not considered dirty when they only
contain untracked content (but they are still scanned for modified
content). Using "dirty" ignores all changes to the work tree of submodules,
only changes to the commits stored in the superproject are shown (this was
the behavior until 1.7.0). Using "all" hides all changes to submodules.

--src-prefix=<prefix>

Show the given source prefix instead of "a/".

--dst-prefix=<prefix>

Show the given destination prefix instead of "b/".

--no-prefix

Do not show any source or destination prefix.

For more detailed explanation on these common options, see also
gitdiffcore(7).
-<n>::
Prepare patches from the topmost <n> commits.

-o <dir>

--output-directory <dir>

Use <dir> to store the resulting files, instead of the
current working directory.

-n

--numbered

Name output in [PATCH n/m] format, even with a single patch.

-N

--no-numbered

Name output in [PATCH] format.

--start-number <n>

Start numbering the patches at <n> instead of 1.

--numbered-files

Output file names will be a simple number sequence
without the default first line of the commit appended.

-k

--keep-subject

Do not strip/add [PATCH] from the first line of the
commit log message.

-s

--signoff

Add Signed-off-by: line to the commit message, using
the committer identity of yourself.

--stdout

Print all commits to the standard output in mbox format,
instead of creating a file for each one.

--attach[=<boundary>]

Create multipart/mixed attachment, the first part of
which is the commit message and the patch itself in the
second part, with Content-Disposition: attachment.

--no-attach

Disable the creation of an attachment, overriding the
configuration setting.

--inline[=<boundary>]

Create multipart/mixed attachment, the first part of
which is the commit message and the patch itself in the
second part, with Content-Disposition: inline.

--thread[=<style>]

--no-thread

Controls addition of In-Reply-To and References headers to
make the second and subsequent mails appear as replies to the
first. Also controls generation of the Message-Id header to
reference.

The optional <style> argument can be either shallow or deep.
shallow threading makes every mail a reply to the head of the
series, where the head is chosen from the cover letter, the
--in-reply-to, and the first patch mail, in this order. deep
threading makes every mail a reply to the previous one.

The default is --no-thread, unless the format.thread configuration
is set. If --thread is specified without a style, it defaults to the
style specified by format.thread if any, or else shallow.

Beware that the default for git send-email is to thread emails
itself. If you want git format-patch to take care of threading, you
will want to ensure that threading is disabled for git send-email.

--in-reply-to=Message-Id

Make the first mail (or all the mails with --no-thread) appear as a
reply to the given Message-Id, which avoids breaking threads to
provide a new patch series.

--ignore-if-in-upstream

Do not include a patch that matches a commit in
<until>..<since>. This will examine all patches reachable
from <since> but not from <until> and compare them with the
patches being generated, and any patch that matches is
ignored.

--subject-prefix=<Subject-Prefix>

Instead of the standard [PATCH] prefix in the subject
line, instead use [<Subject-Prefix>]. This
allows for useful naming of a patch series, and can be
combined with the --numbered option.

--to=<email>

Add a To: header to the email headers. This is in addition
to any configured headers, and may be used multiple times.
The negated form --no-to discards all To: headers added so
far (from config or command line).

--cc=<email>

Add a Cc: header to the email headers. This is in addition
to any configured headers, and may be used multiple times.
The negated form --no-cc discards all Cc: headers added so
far (from config or command line).

--add-header=<header>

Add an arbitrary header to the email headers. This is in addition
to any configured headers, and may be used multiple times.
For example, --add-header="Organization: git-foo".
The negated form --no-add-header discards all (To:,
Cc:, and custom) headers added so far from config or command
line.

--cover-letter

In addition to the patches, generate a cover letter file
containing the shortlog and the overall diffstat. You can
fill in a description in the file before sending it out.

--[no]-signature=<signature>

Add a signature to each message produced. Per RFC 3676 the signature
is separated from the body by a line with -- on it. If the
signature option is omitted the signature defaults to the git version
number.

--suffix=.<sfx>

Instead of using .patch as the suffix for generated
filenames, use specified suffix. A common alternative is
--suffix=.txt. Leaving this empty will remove the .patch
suffix.

Note that the leading character does not have to be a dot; for example,
you can use --suffix=-patch to get 0001-description-of-my-change-patch.

--quiet

Do not print the names of the generated files to standard output.

--no-binary

Do not output contents of changes in binary files, instead
display a notice that those files changed. Patches generated
using this option cannot be applied properly, but they are
still useful for code review.

--root

Treat the revision argument as a <revision range>, even if it
is just a single commit (that would normally be treated as a
<since>). Note that root commits included in the specified
range are always formatted as creation patches, independently
of this flag.

CONFIGURATION

You can specify extra mail header lines to be added to each message,
defaults for the subject prefix and file suffix, number patches when
outputting more than one patch, add "To" or "Cc:" headers, configure
attachments, and sign off patches with configuration variables.

Typically it will be placed in a MUA's drafts folder, edited to add
timely commentary that should not go in the changelog after the three
dashes, and then sent as a message whose body, in our example, starts
with "arch/arm config files were...". On the receiving end, readers
can save interesting patches in a UNIX mailbox and apply them with
git-am(1).

When a patch is part of an ongoing discussion, the patch generated by
git format-patch can be tweaked to take advantage of the git am
--scissors feature. After your response to the discussion comes a
line that consists solely of "-- >8 --" (scissors and perforation),
followed by the patch with unnecessary header fields removed:

...
> So we should do such-and-such.
Makes sense to me. How about this patch?
-- >8 --
Subject: [IA64] Put ia64 config files on the Uwe Kleine-K��nig diet
arch/arm config files were slimmed down using a python script
...

When sending a patch this way, most often you are sending your own
patch, so in addition to the "From $SHA1 $magic_timestamp" marker you
should omit From: and Date: lines from the patch file. The patch
title is likely to be different from the subject of the discussion the
patch is in response to, so it is likely that you would want to keep
the Subject: line, like the example above.

Checking for patch corruption

Many mailers if not set up properly will corrupt whitespace. Here are
two common types of corruption:

Empty context lines that do not have any whitespace.

Non-empty context lines that have one extra whitespace at the
beginning.

One way to test if your MUA is set up correctly is:

Send the patch to yourself, exactly the way you would, except
with To: and Cc: lines that do not contain the list and
maintainer address.

Save that patch to a file in UNIX mailbox format. Call it a.patch,
say.

The patch itself does not apply cleanly. That is bad but
does not have much to do with your MUA. You might want to rebase
the patch with git-rebase(1) before regenerating it in
this case.

The MUA corrupted your patch; "am" would complain that
the patch does not apply. Look in the .git/rebase-apply/ subdirectory and
see what patch file contains and check for the common
corruption patterns mentioned above.

While at it, check the info and final-commit files as well.
If what is in final-commit is not exactly what you would want to
see in the commit log message, it is very likely that the
receiver would end up hand editing the log message when applying
your patch. Things like "Hi, this is my first patch.\n" in the
patch e-mail should come after the three-dash line that signals
the end of the commit message.

MUA-SPECIFIC HINTS

Here are some hints on how to successfully submit patches inline using
various mailers.

GMail

GMail does not have any way to turn off line wrapping in the web
interface, so it will mangle any emails that you send. You can however
use "git send-email" and send your patches through the GMail SMTP server, or
use any IMAP email client to connect to the google IMAP server and forward
the emails through that.

For hints on using git send-email to send your patches through the
GMail SMTP server, see the EXAMPLE section of git-send-email(1).

For hints on submission using the IMAP interface, see the EXAMPLE
section of git-imap-send(1).

Thunderbird

By default, Thunderbird will both wrap emails as well as flag
them as being format=flowed, both of which will make the
resulting email unusable by git.

There are three different approaches: use an add-on to turn off line wraps,
configure Thunderbird to not mangle patches, or use
an external editor to keep Thunderbird from mangling the patches.

Approach #1 (add-on)

Install the Toggle Word Wrap add-on that is available from
https://addons.mozilla.org/thunderbird/addon/toggle-word-wrap/
It adds a menu entry "Enable Word Wrap" in the composer's "Options" menu
that you can tick off. Now you can compose the message as you otherwise do
(cut + paste, git format-patch | git imap-send, etc), but you have to
insert line breaks manually in any text that you type.

Before opening a compose window, use Edit->Account Settings to
uncheck the "Compose messages in HTML format" setting in the
"Composition & Addressing" panel of the account to be used to
send the patch.

In the main Thunderbird window, before you open the compose
window for the patch, use Tools->about:config to set the
following to the indicated values:

mailnews.send_plaintext_flowed => false
mailnews.wraplength => 0

Open a compose window and click the external editor icon.

In the external editor window, read in the patch file and exit
the editor normally.

Side note: it may be possible to do step 2 with
about:config and the following settings but no one's tried yet.

There is a script in contrib/thunderbird-patch-inline which can help
you include patches with Thunderbird in an easy way. To use it, do the
steps above and then use the script as the external editor.

KMail

This should help you to submit patches inline using KMail.

Prepare the patch as a text file.

Click on New Mail.

Go under "Options" in the Composer window and be sure that
"Word wrap" is not set.

Use Message -> Insert file... and insert the patch.

Back in the compose window: add whatever other text you wish to the
message, complete the addressing and subject fields, and press send.

EXAMPLES

Extract commits between revisions R1 and R2, and apply them on top of
the current branch using git am to cherry-pick them:

$ git format-patch -k --stdout R1..R2 | git am -3 -k

Extract all commits which are in the current branch but not in the
origin branch:

$ git format-patch origin

For each commit a separate file is created in the current directory.

Extract all commits that lead to origin since the inception of the
project:

$ git format-patch --root origin

The same as the previous one:

$ git format-patch -M -B origin

Additionally, it detects and handles renames and complete rewrites
intelligently to produce a renaming patch. A renaming patch reduces
the amount of text output, and generally makes it easier to review.
Note that non-git "patch" programs won't understand renaming patches, so
use it only when you know the recipient uses git to apply your patch.

Extract three topmost commits from the current branch and format them
as e-mailable patches: